Fixed bug where there would be an occasional segfault on program start due to calling delete on a null pointer in Scene::changeModel().
Merge branch 'master' of https://github.com/rulises/glsl_toon_shader

Conflicts:
	src/bin.debug/shader_scene
	src/objs.debug/glew.o
	src/objs.debug/glmatrix.o
	src/objs.debug/inverse.o
	src/objs.debug/main.o
	src/objs.debug/matrix_stack.o
	src/objs.debug/menus.o
	src/objs.debug/normalize.o
	src/objs.debug/request_vsync.o
	src/objs.debug/scene.o
	src/objs.debug/sqrt.o
	src/objs.debug/stb_image.o
	src/objs.debug/texture.o
	src/objs.debug/trackball.o
Added minor comment in Scene::changeModel().